Stats Study Sets 4.7-6. Q&A/ Already
Graded A+/ 2024-2025.
(4.7) The transportation department of a large city wants to estimate the proportion of
residents who would use a system of aerial gondolas to commute to work. The gondolas would
be part of the city's effort to relieve traffic congestion. The department asked a random sample
of residents whether they would use the gondolas. The residents could respond with yes, no, or
maybe. Which of the following is the best description of the method for data collection used by
the department? - Answer: A sample survey
(4.7) A school principal wanted to investigate student opinion about the food served in the
school cafeteria. The principal selected at random samples of 50 first-year students, 50 second-
year students, 50 third-year students, and 50 fourth-year students to complete a questionnaire.
Which of the following best describes the principal's sampling plan? - Answer: A stratified
random sample
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,(4.7) Publishers of a magazine wish to determine what proportion of the magazine's 50,000
subscribers are pleased with their subscription. The publishers intend to mail a survey to 1,000
subscribers randomly selected from those who have received the magazine for 5 years or more.
This introduces selection bias, since long-subscribing customers are more likely to be pleased
with their subscription. Which of the following would best eliminate selection bias? - Answer:
Mail surveys to 1,000 subscribers randomly selected from all subscribers.
(4.7) A researcher wanted to estimate the average amount of money spent on extracurricular
activities per school in a certain region. The researcher randomly selected 20 public schools and
20 private schools in the region to use for a sample. Which of the following best describes the
type of sample that was taken? - Answer: A stratified random sample
(4.7) A regional transportation authority is interested in estimating the mean number of
minutes working adults in the region spend commuting to work on a typical day. A random
sample of working adults will be selected from each of three strata: urban, suburban, and rural.
Selected individuals will be asked the number of minutes they spend commuting to work on a
typical day. Why is stratification used in this situation? - Answer: To decrease the variability in
estimates of the mean commuting time
(4.7) Which of the following does not describe a sampling method that has a potential source of
voluntary response bias for the administration of a survey about college athletics at a
university? - Answer: Giving the survey to 30 students selected at random from each of the
eight dorms on campus
(4.7) The student government at a high school wants to conduct a survey of student opinion. It
wants to begin with a simple random sample of 60 students. Which of the following survey
methods will produce a simple random sample? - Answer: Number the students in the official
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, school roster. Use a table of random numbers to choose 60 students from this roster for the
survey.
(4.7) A city planner is investigating traffic congestion at a certain intersection. To collect data, a
camera will record the number of cars that pass through the intersection at different hours of
the day and on different days of the week. Which of the following best describes the type of
investigation being conducted by the city planner? - Answer: The investigation is an
observational study because treatments are not imposed.
(4.7) The buyer for an electronics store wants to estimate the proportion of defective wireless
game controllers in a shipment of 5,000 controllers from the store's primary supplier. The
shipment consists of 200 boxes each containing 25 controllers. The buyer numbers the boxes
from 1 to 200 and randomly selects six numbers in that range. She then opens the six boxes
with the corresponding numbers, examines all 25 controllers in each of these boxes, and
determines the proportion of the 150 controllers that are defective. What type of sample is
this? - Answer: Cluster random sample
(4.7) Eighteen individuals who use a particular form of social media were assigned a new user
interface to use when logging in to their accounts. After using the new user interface for a week,
each individual was asked to rate how easy or hard the new user interface was to use on a scale
from 1 (extremely easy) to 9 (extremely hard). Which of the following correctly identifies why
this is not a well-designed experiment? - Answer: The study was not comparative—only one
treatment was used.
(4.7) A recent study examined 699 car accidents in Toronto over a fourteen-month period.
Records of phone-service providers were used to determine whether the driver was using a cell
phone during or immediately before the accident. Overall, the researchers found that drivers
using cell phones were 4.3 times as likely to have an accident as drivers who were not using cell
phones. The result was statistically significant. Which of the following can be concluded from
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Graded A+/ 2024-2025.
(4.7) The transportation department of a large city wants to estimate the proportion of
residents who would use a system of aerial gondolas to commute to work. The gondolas would
be part of the city's effort to relieve traffic congestion. The department asked a random sample
of residents whether they would use the gondolas. The residents could respond with yes, no, or
maybe. Which of the following is the best description of the method for data collection used by
the department? - Answer: A sample survey
(4.7) A school principal wanted to investigate student opinion about the food served in the
school cafeteria. The principal selected at random samples of 50 first-year students, 50 second-
year students, 50 third-year students, and 50 fourth-year students to complete a questionnaire.
Which of the following best describes the principal's sampling plan? - Answer: A stratified
random sample
Page 1 of 28
,(4.7) Publishers of a magazine wish to determine what proportion of the magazine's 50,000
subscribers are pleased with their subscription. The publishers intend to mail a survey to 1,000
subscribers randomly selected from those who have received the magazine for 5 years or more.
This introduces selection bias, since long-subscribing customers are more likely to be pleased
with their subscription. Which of the following would best eliminate selection bias? - Answer:
Mail surveys to 1,000 subscribers randomly selected from all subscribers.
(4.7) A researcher wanted to estimate the average amount of money spent on extracurricular
activities per school in a certain region. The researcher randomly selected 20 public schools and
20 private schools in the region to use for a sample. Which of the following best describes the
type of sample that was taken? - Answer: A stratified random sample
(4.7) A regional transportation authority is interested in estimating the mean number of
minutes working adults in the region spend commuting to work on a typical day. A random
sample of working adults will be selected from each of three strata: urban, suburban, and rural.
Selected individuals will be asked the number of minutes they spend commuting to work on a
typical day. Why is stratification used in this situation? - Answer: To decrease the variability in
estimates of the mean commuting time
(4.7) Which of the following does not describe a sampling method that has a potential source of
voluntary response bias for the administration of a survey about college athletics at a
university? - Answer: Giving the survey to 30 students selected at random from each of the
eight dorms on campus
(4.7) The student government at a high school wants to conduct a survey of student opinion. It
wants to begin with a simple random sample of 60 students. Which of the following survey
methods will produce a simple random sample? - Answer: Number the students in the official
Page 2 of 28
, school roster. Use a table of random numbers to choose 60 students from this roster for the
survey.
(4.7) A city planner is investigating traffic congestion at a certain intersection. To collect data, a
camera will record the number of cars that pass through the intersection at different hours of
the day and on different days of the week. Which of the following best describes the type of
investigation being conducted by the city planner? - Answer: The investigation is an
observational study because treatments are not imposed.
(4.7) The buyer for an electronics store wants to estimate the proportion of defective wireless
game controllers in a shipment of 5,000 controllers from the store's primary supplier. The
shipment consists of 200 boxes each containing 25 controllers. The buyer numbers the boxes
from 1 to 200 and randomly selects six numbers in that range. She then opens the six boxes
with the corresponding numbers, examines all 25 controllers in each of these boxes, and
determines the proportion of the 150 controllers that are defective. What type of sample is
this? - Answer: Cluster random sample
(4.7) Eighteen individuals who use a particular form of social media were assigned a new user
interface to use when logging in to their accounts. After using the new user interface for a week,
each individual was asked to rate how easy or hard the new user interface was to use on a scale
from 1 (extremely easy) to 9 (extremely hard). Which of the following correctly identifies why
this is not a well-designed experiment? - Answer: The study was not comparative—only one
treatment was used.
(4.7) A recent study examined 699 car accidents in Toronto over a fourteen-month period.
Records of phone-service providers were used to determine whether the driver was using a cell
phone during or immediately before the accident. Overall, the researchers found that drivers
using cell phones were 4.3 times as likely to have an accident as drivers who were not using cell
phones. The result was statistically significant. Which of the following can be concluded from
Page 3 of 28
